Zero Temperature Coefficient Research Articles

Zero temperature coefficient of resistivity induced by photovoltaic effect in Y Ba2Cu3O6.96 ceramics

I-V characteristics of YBCO-Ag system under blue laser (λ = 450 nm) illumination were studied from 100 to 300 K and obvious photovoltaic effects were observed. All the I-V curves in the temperature range intersect at a point in the first quadrant while the laser points to the cathode electrode, indicating a zero temperature coefficient of resistivity. This implies that the outputting voltage keeps constant in a broad temperature range when a critical bias current is assigned. The intersection points of different laser intensities fall in a straight line, the slope of which (Rc) is independent of temperature and laser intensity.

Fabrication of a Hybrid Carbon-Based Composite for Flexible Heating Element With a Zero Temperature Coefficient of Resistance

We report on a hybrid carbon-based composite for zero temperature coefficient of resistance (TCR) heating element, forming edge-island type composite comprised of carbon nanotubes (CNTs) and carbon blacks (CBs) with a polydimethylsiloxane. The island-shaped CB composite is placed between a copper connection electrode and the CNT composite, acting as both a buffer and distribution layer against current flow for a zero TCR. The degree of control over this zero TCR was characterized by examining the thickness ratio between the CNT and CB layers. The optimized edge-island composite structure showed a constant normalized resistance (with <;3% deviation) to 200 °C with a rapid heating property. This edge-island composite structure could be widely used for heat-related or sensor applications, solving safety, and accuracy issues.

Zero temperature-coefficient bias point over wide range of temperatures for single- and double-gate UTB-SOI n-MOSFETs with trapped charges

This paper is a unique attempt to identify the zero-temperature-coefficient (ZTC) point and other performance metrics for single gate (SG), double gate (DG), and gate stack double gate (GS-DG), ultra-thin body (UTB) silicon on insulator (SOI) n-MOSFET over wide range of temperatures (100–400K) through 2-D device simulation. During the pre- and post-fabrication process, availability of the trapped charges is quite common and cannot be neglected in nanoscale devices. Subsequently the effect has been considered in simulation. Simulation results show the existence of a biasing point i.e. ZTC bias point, where the device parameters become independent of temperature. The impact of operating temperature (T) on various performance metrics like on current (Ion), off current (Ioff), on-off current ratio (Ion/Ioff), transconductance (gm), output conductance (gd), intrinsic gain (AV) and cut off frequency (fT) is also subjected to extensive analysis. The variation of ZTC point for transconductance (ZTCgm) and drain current (ZTCIDS) from SG to DG and GS-DG is compared. This further validates the application opportunities involved in designing RF circuits for a wide range of temperature applications.

Structures and electric properties of cubic bismuth based pyrochlore thin films grown by pulsed laser deposition

The effects of cation substitution on the structure, dielectric properties, tunability, and temperature dependence of (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 (BZN) thin films were investigated. Four kinds of ceramic targets and thin films were prepared, which were (Bi1.5Zn0.1Ca0.4)(Zn0.5Nb1.5)O7 (BZNCa), (Bi1.5Zn0.5)(Nb0.5Ti1.5)O7 (BZNTi), (Bi1.5Sr0.5)(Sn1.5Nb0.5)O7 (BSSN) and (Bi1.5Sr0.5)(Zr1.5Nb0.5)O7 (BSZN). Thin films were deposited on Pt/TiO2/SiO2/Si(100) substrates at the substrate temperature of 650°C under an oxygen pressure of 10Pa by pulsed laser deposition. The resultant Bi-based thin films show a cubic pyrochlore structure. Meanwhile, the preferential orientation of the (111) plane is observed. Surface morphology features of the substituted thin films also show the difference. Compared with the pure BZN thin film, the dielectric constant of the BZNCa thin film slightly decreases. The temperature coefficient of capacitance (TCC) moves to the negative orientation TCC=−319ppm/°C. The dielectric constant of the BZNTi thin film significantly increases, reaching 229. At the same time, thin film still keeps the low loss tangent. However, the dielectric constants of the BSSN and BSZN thin films significantly decrease, dropping to 60 and 48, respectively. Furthermore the BSSN thin film exhibits the near zero temperature coefficient of +55ppm/°C. The BSZN thin film also shows the positive TCC value of +318ppm/°C. Moreover, BSSN and BSZN thin films show a near field independence (at low field).

VDMOS electrical parameters potentially usable as mechanical state indicators for power VDMOS assemblies

Power device reliability is a multidisciplinary domain. It requires design and integration of sensors, implementation of signal processing algorithms that allow processing the different data provided by the different sensors in order to predict by statistical means the device failure occurrence and consequently anticipate the power device replacement. Currently, for device ageing studies in a laboratory, electrical measurements of device parameters are often used as an indicator of device ageing. Furthermore, smart metal-oxide semi-conductor technology integrates more and more sensors that permit to measure quantities such as on-state resistance or junction temperature of the device. In power vertical diffused metal oxide semiconductor (VDMOS) assemblies, it would be interesting to make use of the VDMOS electrical parameters deviations in order to monitor the ageing state of the power assembly. To that end, we carry-out in this paper a study mainly based upon electro-thermo-mechanical simulations in order to identify the power VDMOS electrical parameters that could be monitored in order to access to the mechanical state of the power assembly and therefore anticipate the assembly failure. The power VDMOS R on as well as zero temperature coefficient (ZTC) point are of interest because they are sensitive to mechanical stress. Consequently, in this paper, a procedure to minimise temperature impact on the Ron of the VDMOS transistor such that one could use the Ron as mechanical state indicator is shown. Another solution that makes use of a specific operating point of VDMOS (ZTC) which is temperature independent is also studied by simulations and experiment.

Notch frequency of dielectric resonator‐loaded monopole antenna for UWB application

AbstractA dielectric resonator (DR)‐loaded monopole antenna with band‐notched characteristics is proposed for ultrawideband applications. The proposed antenna consists of a microstrip fed circular monopole printed on a FR4 substrate loaded with a DR, having relatively high dielectric constant and near zero temperature coefficient of the resonant frequency (τf) compared with FR4. A wide bandwidth from 2.966 to more than 12 GHz, omitting the undesired frequency band of 5.15–5.9 GHz with a reference level of S11 = −6 dB can be obtained. The gain and surrounding environment temperature stability can be enhanced by mounting the GYA DR. Experimental and simulated results showed a good agreement. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1189–1193, 2014

A new temperature stable microwave dielectric ceramic with low-sintering temperature in Li2TiO3–Li2Zn3Ti4O12 system

The crystalline phases, microstructure, composition analysis and microwave dielectric properties of Li2TiO3–xvol.% Li2Zn3Ti4O12 (x=15–40) composite ceramics with 1–3wt.% Li2O–ZnO–B2O3 (LZB) glass addition prepared by solid-state reaction method have been investigated. A near zero temperature coefficient of resonant frequency (τf) of about −1.3ppm/°C was obtained in the Li2TiO3–30vol.% Li2Zn3Ti4O12 ceramic sintered at 1100°C for 2h with permittivity of 22.0, Q×f value of 38,900GHz. The microwave dielectric properties of Li2TiO3–20vol.% Li2Zn3Ti4O12 ceramics with 1–3wt.% LZB glass addition sintered at 900°C for 2h were characterized. The addition of 2.5wt.% LZB glass reduced the sintering temperature of the Li2TiO3–20vol.% Li2Zn3Ti4O12 ceramic from 1100°C to 900°C without obvious degradation of the microwave dielectric properties. The 2.5wt.% LZB glass-added Li2TiO3–20vol.% Li2Zn3Ti4O12 ceramic sintered at 900°C for 2h could reach a high relative density of 98% of the theoretical density of the Li2TiO3–20vol.% Li2Zn3Ti4O12 ceramic and exhibited microwave dielectric properties of ɛr=22.0, Q×f=28,407GHz, and a near zero τf value of −1.6ppm/°C. Moreover, this ceramic has a chemical compatibility with Ag electrode, making it a very promising candidate material for Low-temperature co-fired ceramic (LTCC) applications.

A Temperature Compensation Circuit within Constant Current Charging Cycle

A CMOS temperature compensation circuit within constant current charging cycle is proposed in the paper. The circuit is composed by a positive temperature coefficient current source, a current source with zero temperature coefficient and a relevant operational circuit, and can make balance between heat production and dissipation during trickle charging and constant current charging. Finally, with the CSMC 0.5um CMOS process, the simulation can get the temperature characteristic curve of intelligent heat adjusting current. The temperature compensation circuit is especially suitable for the application in different charging system.

Resolving the bias point for wide range of temperature applications in High-k/Metal Gate nanoscale DG-MOSFET

This article investigates the Zero-Temperature-Coefficient (ZTC) bias point and its associated performance metrics of a High-k Metal Gate (HKMG) DG-MOSFET in nanoscale. The ZTC bias point is defined as the point at which the device parameters are independent of temperature. The discussion includes sub threshold slope (SS), drain induced barrier lowering (DIBL), on-off current ratio (Ion/Ioff), transconductance (gm), output conductance (gd) and intrinsic gain (AV). From the results, it is confirmed that there are two different ZTC bias points, one for IDS (ZTCIDS) and the other for gm (ZTCgm). The points are obtained as: ZTCIDS=0.552 V and ZTCgm =0.410 V, which will open important opportunities in analog circuit design for wide range of temperature applications.

A high Q and temperature stable microwave dielectric ceramic Ba4LiTa2SbO12

A low loss and temperature stable microwave dielectric ceramic Ba4LiTa2SbO12 with 8H hexagonal perovskite structure was prepared by traditional solid-state ceramic route. Sintering behavior, phase transformation, and microwave dielectric properties of Ba4LiTa2SbO12 ceramics were studied. X-ray diffraction analysis indicated that a phase transition from cubic to hexagonal perovskite occurred when calcined temperature increased from 1300°C to 1500°C. Ba4LiTa2SbO12 ceramic sintered at 1480°C exhibited optimum microwave dielectric properties with a moderate relative permittivity of ~25.1, a high quality factor (Qu×f) of ~77,700GHz, and a near zero temperature coefficient of resonant frequency (τf ) of −3.6ppm/°C.

Preparation, structural and microwave dielectric properties of CaLa4(ZrxTi1−x)4O15 ceramics

• New microwave dielectric properties of CaLa 4 (Zr x Ti 1 − x ) 4 O 15 ceramics were investigated. • A significant improvement of dielectric constant and τ f were achieved by CaLa 4 (Zr x Ti 1 − x ) 4 O 15 system. • Second phases were formed and affected the dielectric properties of CaLa 4 (Zr x Ti 1 − x ) 4 O 15 system. • The ε r of 46, Q f ∼ 47,500 GHz, and τ f ∼ −9.5 ppm/°C were obtained for CaLa 4 (Zr 0.05 Ti 0.95 ) 4 O 15 ceramics. Hexagonal-phase CaLa 4 (Zr x Ti 1 − x ) 4 O 15 ( x = 0.01–0.1) with excellent microwave dielectric properties are candidate materials for microwave dielectric resonators. An excess of Zr 4+ resulted in the formation of a secondary phase of CaLa 4 Ti 5 O 17 , affecting the microwave dielectric properties of the CaLa 4 (Zr x Ti 1 − x ) 4 O 15 ceramics. By increasing x from 0.01 to 0.05, the dielectric constant and Q × f value of the specimen could be increased from 45.8 to a maximum of 46, and from 44,800 GHz to a maximum of 47,500 GHz at a sintering temperature of 1550 °C, respectively. The zero temperature coefficient of the resonant frequency of the CaLa 4 (Zr x Ti 1 − x ) 4 O 15 ceramics also improved with increasing Zr content.

Compact Zero-Temperature Coefficient Modeling Approach for MOSFETs Based on Unified Regional Modeling of Surface Potential

A compact zero-temperature coefficient (ZTC) modeling approach is demonstrated for generic MOSFETs. Instead of manually extracting ZTC points through <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> or <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> data over a range of operating temperatures, the ZTC model marks the cross-over ZTC points by Newton-Raphson solutions to the ZTC voltages based on the compact charge/current models. It calculates the ZTC voltages in the accumulation ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztc,sa</sub> ) and depletion ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztc,ds</sub> ) regions based on the unified regional modeling of surface potential for the gate capacitance at zero drain bias ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> =0). It is extended to the ZTC voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztc,ds</sub> ) for gate capacitance in the depletion and saturation regions at any <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> , and the ZTC voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ztc</sub> ) for drain current in the linear and saturation regions at any <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> . The proposed approach can be adopted to create a process window with constant ZTC contours for different process parameters, such as body doping and gate-oxide thickness at any drain biases. The process windows provide useful information in determining the optimum process parameters and operating voltages for circuit design in ruggedized electronics that operate at high-temperature conditions.

Impacts of Multiple Strain-Gate Engineering on a Zero-Temperature-Coefficient Point

The impacts of zero-temperature-coefficient (ZTC) points of various strained devices is presented in this paper. The current and mobility are reduced at high temperature by phonon scattering. The degree of mobility reduction becomes severe on devices with multiple strain-gate engineering. The reduction of mobility becomes severe as a result of impurity scattering, which results from gate implantation impurities. The ZTC point is decreased by multiple strain-gate engineering due to the decreased Vth.

Turnover Temperature Point in Extensional-Mode Highly Doped Silicon Microresonators

This paper demonstrates the existence of a local zero temperature coefficient of frequency (i.e., turnover point) in extensional-mode silicon microresonators, fabricated on highly n-type-doped substrates and aligned to the [100] crystalline orientation. It is shown through both theoretical analysis and finite-element simulation that the turnover point in thin-film piezoelectric-on-silicon (TPoS) resonators is a function of doping concentration and orientation. Moreover, the turnover point can be adjusted by changing the thickness ratio of Si and the piezoelectric film (e.g., AlN) in the resonant structure. In order to experimentally validate this result, similar resonators are fabricated on silicon-on-insulator substrates, and the temperature variation of frequency is measured. An overall temperature-induced frequency variation of less than 245 ppm is measured over the range of -40 °C-85 °C for an ~ 25-MHz TPoS resonator aligned to the [100] plane. This is more than a 15-times reduction with respect to the uncompensated conventional silicon resonators reported before. This work is a significant step toward strengthening silicon's position as an alternative resonator technology in the quartz-dominated stable oscillator market.

The zero temperature coefficient in junctionless nanowire transistors

This Letter presents an analysis of the zero temperature coefficient (ZTC) bias in junctionless nanowire transistors (JNTs). Unlike in previous works, which had shown that JNT did not present a ZTC point, this work shows that ZTC may occur in JNTs depending mainly on the series resistance of the devices and its dependence on the temperature. Experimental results of drain current, threshold voltage, and series resistance are presented for both long and short channel n and p-type devices.

Transverse-Mode Spurious Suppression Technique for Surface Acoustic Wave Resonator with Zero Temperature Coefficient of Frequency on a SiO2/Al/LiNbO3 Structure

In this paper, we describe a suppression technique of transverse-mode spurious responses for a surface acoustic wave (SAW) resonator with a near zero temperature coefficient of frequency (TCF) on a SiO2/Al/LiNbO3 structure. We investigated the thinning of SiO2 on the dummy electrode region and studied how the transverse-mode responses change with remaining SiO2 thickness h on the dummy electrode region. As the results, we clarified that the remaining SiO2 thickness h on the dummy electrode region has an optimum value and could suppress the transverse-mode spurious responses completely when H and h are set at 0.35 λ and 0.20 λ, respectively. It was demonstrated that the selective SiO2 removal technique is effective to suppress transverse-mode spurious responses for SAW resonators employing the SiO2/Al/LiNbO3 structure for a wide range of SiO2 thicknesses, provided that the SiO2 thickness at the dummy electrode region is adjusted properly.

CVD silicon carbide electric heaters

This paper describes the growth of tubular polycrystalline 3C-SiC samples by chemical vapor deposition (CVD). The use of propionitrile as a precursor for nitrogen doping ensures the growth of polycrystalline 3C-SiC layers with a 1000°C resistivity of 0.1–0.2 Ω cm and zero temperature coefficient of resistance. Such 3C-SiC tubes can be used as silicon carbide electric heaters.

Numerical analysis of the influence of two-phase flow mass and heat transfer on n-heptane autoignition

This paper investigates the influence of liquid fuel presence on the autoignition of n-heptane/air mixtures over a wide range of conditions encountered in internal combustion engines. To this end, evaporating droplet physics and skeletal chemistry mechanisms are simultaneously solved considering a homogeneous constant-pressure reactor. A skeletal mechanism is introduced to account for specific kinetics behavior in the Negative Temperature Coefficient (NTC) region. The impact of mass and heat source terms during evaporation is emphasized by comparing a two-phase flow scenario with a purely gaseous case. The competition between fuel vapor availability and the evaporation-induced gas temperature decrease is specific to two-phase flow autoignition. On the one hand, droplet evaporation delay restricts the gaseous local fuel/air equivalence ratio and consequently the kinetics runaway. On the other hand, temperature reduction due to evaporation may either reduce or enhance chemical reactivity, depending on the local thermodynamic conditions lying either inside or outside the NTC region. By simultaneously accounting for evaporation source terms and skeletal chemistry, we can reproduce the already experimentally observed transformation of the NTC region into a Zero Temperature Coefficient (ZTC) region depending on thermodynamic conditions and droplet size. The ZTC phenomenon appears when combustion heat-release starts before complete droplet evaporation. Since the ZTC behavior can be captured using the point source approach, in which droplets are considered only as zero-dimensional source terms of mass and energy, the present results pave the way for future exploration of NTC chemistry in sprays with a direct numerical simulation of discrete particles considering detailed chemistry and turbulent flows.

Temperature characteristics of Schottky barrier diodes for low-voltage sensing applications

N-type Si Schottky barrier diodes (SBDs) have been fabricated in AMI 0.5 m process. The I-V characteristics have been characterised from -50 to 120-C. The bias voltages for achieving the zero temperature coefficient (ZTC) point were observed to be around 0.6-V, which are much smaller than the voltages for metal-oxide-semiconductor field-effective transistors (MOSFETs) to obtain the same point. A physical model was extracted for the SBDs, demonstrating the low ZTC-point-bias-voltages which are advantageous for low-voltage applications.

Near zero temperature coefficient of resistivity in antiperovskite Mn3Ni1−xCuxN

The near zero temperature coefficient of resistivity (NZ-TCR) in Mn-based antiperovskite Mn3Ni1−xCuxN is reported. The temperature range of NZ-TCR is controllable by changing Cu content. Further, the TCR value of 0.09 ppm K−1 was obtained in Mn3Ni0.5Cu0.5N over a broad temperature range around room temperature. The anomalous resistivity change of Mn3Ni1−xCuxN from metal-like to NZ-TCR behavioris apparently due to a magnetic transition. The possible reason for the formation of NZ-TCR is interpreted on the basis of spin-disorder scattering.